Imagined vs. Actual Recoil

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roy reali

New member
There are many you here that have more technical and scientific skills then I do. As simply as you can describe it, what all actually goes into recoil. Please put it in English.

Some shooters say that some guns' recoil is more of a shove while others are more like a jolt. Is there any truth to this. How does the recoil energy of a .30-06 compare to a 12 gauge shotgun in a number sense?

I have shot both. A shotgun does seem more like a shove and a rifle seems to be more like a jab. I have fired dozens of shots through a shotgun in one sitting with hardly any discomfort. I have shot deer rifles that if I shot that many rounds through in a short time I would have a sore shoulder.

Also, is there any evidence that muzzle blast is a contributor to felt recoil? I have often heard that louder guns seem to kick more. Any truth to it?

Is there mathematical evidence to this or is it just in my head.
 
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MLeake

New member
Not a scientific test, but entertaining...

... I remember a Guns & Ammo article on the .460 Weatherby Magnum, back in the 80's.

For a lark, the staffers got an old Radio Flyer wagon, and a clear, flat, paved area. They then had a couple of shooters fire different rifles, including the .460, while in the wagon.

They measured how far the wagon moved back after each shot.

Not surprisingly, the female staffer got moved farther back than the male did, with any chosen caliber.

Also not surprisingly, the .460WM generated a fair amount of wagon travel.
 
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Regolith

New member
I have shot both. A shotgun does seem more like a shove and a rifle seems to be more like a jab. I have fired dozens of shots through a shotgun in one sitting with hardly any discomfort. I have shot deer rifles that if I shot that many rounds through in a short time I would have a sore shoulder.
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Try shooting a slug through the shotgun. I can fire around 10 to 15 shots through my .30-06 before it starts to become really uncomfortable. I reach the same level of discomfort after just a couple of 2 3/4" 1 oz 12 gauge slugs. The rifle feels like a jab, the shotgun with slugs feels like a sucker punch.
 
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MLeake

New member
As far as perceived recoil goes...

... there are a couple more factors to consider (at least a couple).

1) What kind of recoil pad, if any, do you have on the firearms in question?

2) What position are you shooting from?

3) What configuration firearm (action, weight, etc) are you using?

I shoot my .30-06 rifles mostly from the bench or prone, whereas (with shot shells) I normally shoot my 870's from standing. Standing position allows the body to rock more with the recoil, and dissipate more recoil energy. Bench and prone keep the shoulder more stabilized, so it absorbs more force.

I have a Limbsaver on my Rem700 - which I added after my first day at the range with the stock recoil pad. Perceived recoil dropped way, way down. With the Limbsaver, I very comfortably fired a 20rd box of .30-06 to sight in a scope at 100 yds, and another ten rounds seeing what it would do at 200, and noticed only minimal stiffness an hour or so later.

Ok, so I could have done it in fewer rounds... I was having fun.

My M1 Garand is stock, no added pads. However, it's heavy, and its mass helps absorb a lot of recoil energy. So does the semi-auto action.

My 870 has a Galco slip-on recoil pad. I can shoot shot all day out of it. Slugs aren't as pleasant, but aren't bad.

Slugs from the 12ga 870 (to me) have a very similar perceived level of recoil as 180gr bullets from the Rem700. The .30-06 is a bit sharper; the 12ga slug feels like a deeper push. An hour later, my shoulder feels about the same with either weapon.
 
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roy reali

New member
Velocity

Thanks to your responses.

But isn't there something called recoil velocity? Is there a formula for that?
 
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wally626

New member
But isn't there something called recoil velocity? Is there a formula for that?
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See http://www.scribd.com/doc/3630045/hatchers-notebook for lots of discussion of recoil and many other topics.

You can calculate a relative level of recoil between two guns or type of ammunition. The bullet speed and velocity gives you the momentum imparted by the bullet and the guns mass gives you a rough idea of how much of the recoil will be felt by you. Essentially Mass(bullet) x Velocity(bullet) = Mass(gun) x Velocity(gun). If you read Hatcher's sections discussing recoil you will find the real answer is much much more complex.
 
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roy reali

New member
re:wally626

Thanks for the link.

I have also heard that the size of the shooter matters. But not in the expected way. I have heard that shooters of slight build might actually tolerate recoil better then large shooters.

Light shooters will have more of their body move under recoil. They are more springy. A big shooter's body doesn't have as much give therefore the recoil is absorbed more. This is espically true in their shoulder.

Don't ask me why, recoil has always fascinated me.
 
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44 AMP

Staff
There are many factors in felt recoil...

In recoil energy, there is only the energy of the ejecta (bullet and powder gas) and the weight of the gun. Generally we ignore the mass of the powder gas, except in the most precise calculations. That leaves the energy of the bullet (x amount of mass at y speed) and the mass of the gun.

Newton's third law of physics applies. Equal force in both directions. The same energy pushing the bullet out is pushing the gun back. The difference in the mass (weight for us uneducated folks) determines the speed (velocity) of the gun in recoil. A 12ga slug fired in an 8lb shotgun has the same recoil energy as the same slug fired in a 6lb gun. But the lighter gun will have a higher recoil velocity, and that velocity is what we feel as a harder "kick".

There are many factors that go into "felt recoil", including gun weight, stock design (and how it fits the particular shooter), and shooter tolerance. Also included should be the shooter's position when the gun fires.

The amount of drop in the stock, the size, composition, and shape of the buttplate, the shooter's position (upright, prone, etc.) all have an effect on what the shooter feels.

Calculated recoil energy is useful for comparisons, but has little relationship to what the shooter actually feels, other than in a general sense.

It is a very individual thing.
 
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Sevens

New member
I've seen so many instances where the cartridge chambered seems to be just an early indicator of what might be delivered in felt recoil but in actual practice, you feel something so much different than you might have expected because of a half dozen or more other factors.

I will give my own personal examples and while they may not sound like they make a lot of sense I can only back them with my word -- I'm not making any of these up.

.380... yeah, puny little .380 from any of the unlocked breech cheaper pistols is a snappy little SOB that jars the hand with each and every shot. The Bersa Thunder is a good example. But then shoot .380 from a proper locked beech action like the tiny Sig P238 or the large and light PK-380 and it's a little popper that you could shoot all day and never have any fatigue from.

9mm from a Glock 19... which I thought would be a *****cat seemed to be quite a little jolt for such a small round and a round that I've been shooting for what, 20 years? I had shot it from a Glock before but not since the late 1980s. When I picked one up recently I was expecting a bunch of nothing but what I found was a snappy little SOB that wasn't nearly as wimpy as I was expecting.

Sounds odd maybe, especially to Glockophiles. But my EDC is a Glock 29. 10mm! Sure, it recoils more than a Glock 19, but not so much more that you wet yourself. In fact, last week I confirmed something that I've suspected for years. The Glock 29 gives me less felt recoil than my S&W 1006. Yeah, the 1006 is a monster... big, heavy, huge grip, spreads the recoil, right? I loaded up two mags for each pistol with the exact same ammo and then alternated magazines through them and I have no doubt... the Glock 29 snaps less and feels nicer to shoot than the much larger and heavier 1006. I think it has to do with the geometry of the pistol and where the chamber is in relation to where it sits in your hand.

I shot a S&W 460XVR and was expecting real pain... but the load we had in it was the 200 grain Hornady FTX load. Certainly not a heavy-for-caliber pill, but still, .460 right? Wow, it was a *****cat. Lots of boom, flash and thunder... Rolling recoil, sure, but pain? Not even close. But try a .44 Mag from my 10-inch Contender and I'll bet you can't get through half a box. They are awful.

My buddy has a T/C Encore Pro Hunter in .300 Win Mag with the flex-tech stock. This setup so very much tames recoil that you will NOT believe it until you shoot it. 150gr .300 WM max load handloads feel nice to shoot. But 7mm Mag from a Savage lightweight with a plastic stock? I though I was going to loosen some molars. And .500 Mag from a differ T/C Encore without the flex-tech stock? That was 5 rounds of pure pain.

There's a lot at work in felt recoil and while some of it is certainly mental, I don't think that's a significant part of it. I think the dimensions and geometry of the platform has a large bearing on it, as much as chambering/caliber do.
 
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Frank Ettin

Administrator
Recoil energy and felt (perceived) recoil are two different things. 



Recoil energy is a precise, physical quantity that is a function of the weight (mass) of the bullet, the weight (mass) of the powder charge, the muzzle velocity of the bullet, the muzzle velocity of the powder gases, and the weight (mass) of the gun. If you have those quantities for a given load in a given gun, you can calculate the amount of recoil energy produced when that load is fired in that gun.



Felt recoil is a subjective matter. It's how you experience the recoil, and it's really something that only you can decide for yourself. 

In general, for example, a lighter, fast bullet may produce recoil energy comparable to that of a heavier, slower bullet. But the recoil energy of the load with the lighter bullet will be manifest in a shorter pulse (distributed over a shorter period of time), while that with the heavier bullet will be distributed over a longer period of time. Depending on how you, personally experience these two types of recoil pulses, one may seem greater to you than the other, even though they really have similar recoil energy.

Other factors can also affect felt recoil. With a long gun gun fit can have an effect. A rifle with less drop at the comb will recoil more straight back than one with greater drop at the comb, and so the recoil pulses of the two will seem different even when everything else is equal. Things like recoil pads and the width of the butt can also affect how the recoil is felt.

Things like muzzle flash or noise, while not really related to recoil, can still affect how it is felt. They can increase the total sensory input at the time of firing, which some folks can translate to "more felt recoil."



If you're interested, you can calculate the recoil energy of a given load using the following formula:



WG = Weight of gun in pounds


WB = Weight of bullet in grains


WP = Weight of powder charge in grains


VB = Muzzle velocity of bullet in f/s


I = Interim number (Recoil Impulse in lb/sec)


VG = Recoil velocity of gun (f/s)


EG = Recoil energy of gun (ft lb)



I = [(WB * VB) + (WP * 4000)] / 225218

VG = 32.2 * (I / WG)



EG = (WG * VG * VG) / 64.4



This formula is quite similar to a formula for free recoil set out at http://en.wikipedia.org/wiki/Free_recoil, although I think that the formula from Wikipedia may be a little more precise based on what I've read in Hatcher's Notebook. The formula I've reproduced above, is from the Q&As at http://www.frfrogspad.com/miscella.htm (specifically the question about why some guns of the same caliber kick harder than others). John Schaefer (FrFrog) notes that, "..."4000" is the nominal velocity of the powder gases at the muzzle for commercial smokeless powder and the observed range is between 3700 and 4300 f/s. It is sometimes stated as 4700 in some sources but this is based on observations of artillery, not small arms...." The Wikipedia formula would use the actual powder gas velocity, which may not be readily available.
 
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roy reali

New member
Shooter's Size

I have heard that smaller shooters may actually tolerate long gun recoil better then larger shooters. Anyone heard of this? Any truth to it?
 
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Brian Pfleuger

Moderator Emeritus
Roy Reali said:
I have heard that smaller shooters may actually tolerate long gun recoil better then larger shooters. Anyone heard of this? Any truth to it?
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I've never heard of that and I've never noticed it to be true. Quite the opposite, actually.

The differences become apparent when the cartridge in question gets to be enough where the recoil can actually do damage. Somewhere in the 30-06 range is about it. Once you get in that neighborhood, the recoil becomes unpleasant for almost everyone, within a few shots, no matter how "right" you hold the gun.

Lower recoil guns that still have some appreciable recoil, like a 243 or 25-06, can be thought rather unpleasant by some folks that are smaller if they don't handle the gun properly. Bigger people, generally, have a higher threshold of recoil where holding the gun properly starts to matter. A 120lb, 15yr old kid might find a 243 to be decidedly unpleasant if held incorrectly, where his 230lb father can fire the thing free-floating on his arm and not care.

Anyway, the real answer is that recoil sucks and it's almost never necessary to use a gun that beats you up. Something in the low 7mm range is more than adequate for virtually any animal in North America, certainly elk, black bear, moose and the like, and still has quite manageable and not unpleasant recoil. Even a 243 is fine for most anything below moose.

You don't need to hunt whitetail deer with a 338 magnum.:rolleyes:
 
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Frank Ettin

Administrator
peetzakilla said:
...the real answer is that recoil sucks and it's almost never necessary to use a gun that beats you up...
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Recoil is also cumulative and fatiguing. Most of us shooting trap prefer lighter loads and heavier guns. Sure, a 11/8th oz./3 dram load, the maximum permitted in competition, is very manageable in an 8.5 to 9.5 pound gun. But in competition we'll shoot 200 to 300 targets in a day, plus practice and, if you're lucky, shoot-offs. In a major competition that might run four to seven days, that's a lot of shooting. The cumulative recoil effect of a high volume of shooting is one reason that some competitive trap shooters develop a flinch and switch to a release trigger.

When I was competing regularly, I favored 1 oz./2.75 dram loads, as do many. But after the full program at the State Shoot (1,700 targets over 8 days), I was pretty tired of even the milder felt recoil of the lighter load.
 
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brickeyee

New member
The basic methods for recoil energy are simple.

The weight of everything coming out the barrel and its velocities (including the powder weight and an estimate of the velocity of the gasses) is used to compute the momentum of the ejecta.

The weight of the gun is then used to compute a recoil velocity for the gun.

This recoil velocity is then used with the mass of the gun to compute an energy (0.5mv^2).

This is the energy the shooter is going to have to 'dissipate' to stop the guns movement.

How it feels is a separate issue.

Gun fit to the shooter, how the gun is held, the speed of the bullet acceleration (AKA 'jerk') all start to come into play.

Big slow bullets tend to produce a longer acceleration time and often appear more as a push than a sharp slap like a smaller higher velocity load does.

The actual free recoil energy is just the starting point.

My brother has a pump action .30-06 that kicked like a mule till the angle of the but was corrected.

Every shot smacked your face hard.
A little less angle and it became much more pleasant to fire.
The gun went backwards more than upwards after the change.
 
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Kreyzhorse

New member
I have heard that smaller shooters may actually tolerate long gun recoil better then larger shooters. Anyone heard of this? Any truth to it?
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I think recoil is so widely perceived by different folks that you would be hard pressed to make a general statement that "smaller shooters tolerate recoil better than larger shooters."

As well outlined above, there are a lot of factors that make up recoil. How a human "feels" under that recoil vs another human is much more complicated and very individual.
 
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